From mboxrd@z Thu Jan  1 00:00:00 1970
From: Leon Romanovsky <leon-2ukJVAZIZ/Y@public.gmane.org>
Subject: Re: [PATCH] i40iw: Remove unnecessary synchronize_irq() before
 free_irq()
Date: Wed, 30 Mar 2016 10:15:03 +0300
Message-ID: <20160330071503.GB8511@leon.nu>
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To: Lars-Peter Clausen <lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org>
Cc: Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Faisal Latif <faisal.latif-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Chien Tin Tung <chien.tin.tung-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Mustafa Ismail <mustafa.ismail-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Shiraz Saleem <shiraz.saleem-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Tatyana Nikolova <tatyana.e.nikolova-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Sean Hefty <sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Hal Rosenstock <hal.rosenstock-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
List-Id: linux-rdma@vger.kernel.org

On Mon, Mar 28, 2016 at 11:31:26AM +0200, Lars-Peter Clausen wrote:
> Calling synchronize_irq() right before free_irq() is quite useless. On one
> hand the IRQ can easily fire again before free_irq() is entered, on the
> other hand free_irq() itself calls synchronize_irq() internally (in a race
> condition free way), before any state associated with the IRQ is freed.
> 
> Patch was generated using the following semantic patch:
> // <smpl>
> @@
> expression irq;
> @@
> -synchronize_irq(irq);
>  free_irq(irq, ...);
> // </smpl>
> 
> Signed-off-by: Lars-Peter Clausen <lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org>

Thanks
Reviewed-by: Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>

> ---
>  drivers/infiniband/hw/i40iw/i40iw_main.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/infiniband/hw/i40iw/i40iw_main.c b/drivers/infiniband/hw/i40iw/i40iw_main.c
> index 90e5af2..006c44f 100644
> --- a/drivers/infiniband/hw/i40iw/i40iw_main.c
> +++ b/drivers/infiniband/hw/i40iw/i40iw_main.c
> @@ -270,7 +270,6 @@ static void i40iw_disable_irq(struct i40iw_sc_dev *dev,
>  		i40iw_wr32(dev->hw, I40E_PFINT_DYN_CTLN(msix_vec->idx - 1), 0);
>  	else
>  		i40iw_wr32(dev->hw, I40E_VFINT_DYN_CTLN1(msix_vec->idx - 1), 0);
> -	synchronize_irq(msix_vec->irq);
>  	free_irq(msix_vec->irq, dev_id);
>  }
>  
> -- 
> 2.1.4
> 
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